Following are some acronyms used in the text below and in certain of the figures:                DVB-H digital video broadcasting—handheld        E-UTRAN evolved UTRAN (also known as 3.9 G or long term evolution LTE)        GPS global positioning system (e.g., Glonass, Galileo)        GSM global system for mobile communications        ISM industrial, science, medical        UTRAN universal mobile telecommunications system terrestrial radio access network        LTE long term evolution        WCDMA wideband code division multiple access        WLAN wireless local area network        WiMAX worldwide interoperability for microwave access        
Use of and research into what is termed multiradio devices is a growing trend in wireless communications. They enable the user to take advantage of increased network coverage at hotspots covered by another radio technology, they enable users to access wide area networks (e.g., traditional cellular) and more localized networks (e.g., Bluetooth with a headset or a personal computer PC) either separately or simultaneously, and in some instances enable the wireless device to act as a mobile router for other traffic. A multiradio device user can then optimize costs by, for example, handing over to a radio technology network in which the user pays a flat rate or reduced rate as compared to other available networks, or use a free/low cost network (e.g., WLAN) to which s/he has access for more voluminous data downloads as opposed to another network that charges on a volume basis for data. Different networks may price differently for voice, data and/or broadcast, and the multiradio device can take advantage of cost arbitrage across these different networks and signal types.
These advantages are not without technical challenges. Device manufacturers as well as network operators must assure that quality of service QoS is preserved across the various networks they support, and particularly for portable multiradio device manufacturers power consumption becomes again a major concern. Coexistence of the different transceivers must fulfill certain system-specific requirements in order to maintain a high QoS, such as, harmonics, noise attenuation and blocking. Generally these are accomplished via various filters in the transmitters and receivers of these radios.
One aspect of the necessary isolation between the various radios of a multiradio device is isolation between antennas, termed in the art as minimum coupling loss MCL. For example MCL can be set to any fixed value and filtering requirements are based on that assumption. The specific filtering implemented in a particular device depends on front end band combinations and the antenna systems being used, whether single feed, dual feed, multi feed, or separate transmit and receive antennas to name a few common antenna systems. Filtering also depends on whether different cellular and complementary radios of the device use the same antenna, the frequencies in use at the same antenna, and case (housing size) requirements for multiradios.
The size of the multiradio device is limited by technical design factors. External or whip type antennas are giving way to internal antennas (e.g., planar inverted F-antenna PIFA for example) and even in the case of whip monopole antennas there is commonly a retractability feature that poses a design consideration for putting together all necessary components in a small device. Antennas occupy precious volume within the device housing and they need to have a certain placement in the device, both relative to other internal components and to how a user would hold the device (if the multiradio is handheld as many are) to either avoid or exploit coupling with the user's body. This concern for placement is to achieve an acceptable total radiated power/total radiated sensitivity TRP/TRS, which are metrics in the wireless arts for antenna performance. The various antennas for the various radios of a multiradio device need to be combined together to fit into the device housing. How they may be combined or disposed relative to one another is limited by the MCL requirements and what is a feasible bandwidth of an individual antenna at a certain antenna size. If the number of the needed antennas can be reduced, then the remaining antennas can be bigger in volume and thus the radiating efficiency of the single antenna (or the fewer antennas) can be improved.
If the radio frequency RF air-interface is generating interferences to the wireless terminal receivers, then transceiver communication performance is either degraded or the air-interface connection does not work at all. There are also technical challenges in designing the RF engine within the multiradio device. Typically, verification of a new RF engine design takes months, and requires dedicated frequency-variant verification resources during development of that RF engine. The RF front end, nearest the antenna, has grown to modules of increasingly complexity and cost. This complexity is seen in a greatly increased number of switches, which in the transmitter and receiver generates TRP, TRS and harmonics problems. The number of cellular and complementary antennas is increasing in multiradio devices as more networks are supported, and this trend is expected to continue. For example >2.6 GHz transceiver systems with antennas are anticipated for the near future, to support for example LTE (EUtran), WiMAX and WLAN 5 GHz. Interoperability to meet the required MCL isolations then becomes even more difficult to achieve between antennas. An increased number of antennas increases basic costs and an increasing amount of metallization within the multiradio device further limits placement options for these added antennas.
There are also co-existence interoperability requirements between cellular and complementary transceivers so that different ones of the radios can be used at the same time. For this the following issues need to be solved:                WCDMA LTE band VII (2.6 GHz) transmitter generated noise to ISM (WLAN) band, with current filtering (bulk acoustic wave BAW or surface acoustic wave SAW) technology        GSM/WCDMA/CDMA transmitter harmonics, a wide band noise and an adjacent and an alternative channel power leakage overlaps multiple terrestrial and mobile television channels and channel allocations, GPS band and ISM band allocations at 2.4 GHz and 5 GHz frequency ranges.        Cellular harmonics falling to 2.4 GHz and 5 GHz WLAN and WiMAX 3.4 GHz systems        WLAN, Bluetooth, WiMAX and 3.9 G operate all at 2.3-2.7 GHz band:                    a. WLAN at 2400-2497 MHz;            b. Bluetooth at 2400-2484 MHz            c. WiMAX at 2300-2400, 2490-2690, and 3400-3800 MHz;            d. LTE (3.9 G) at 2500-2690 MHz.                        
One prior art approach to addressing the RF front end in a multiradio device is seen at European Patent Application EP 1311063 A1. FIG. 10 of that reference is reproduced at FIG. 1a of this paper, and is seen to use a diplexer 81 to couple an antenna ANT to a duplexer 90 via a high frequency switch circuit 85. Another approach is seen at U.S. Pat. No. 6,683,513, of which FIG. 1 of that reference is reproduced as FIG. 1b herein. This approach uses an electronically tunable RF diplexer 10 tuned by tunable capacitors in filters 12, 14. Yet another prior art approach is seen at US Patent Publication No. US2003/0022631 A1 (of which FIG. 2 of that reference is reproduced herein as FIG. 1c) that describes a multi-mode bidirectional communications device including a diplexer 130 having a switchable notch filter 134. And finally, shown as FIG. 1d herein is a diagram of a tunable filter device which was taken from an advertisement by the WiSpry Company of Irvine, Calif., USA. Other documents give various details for the tunable duplexers cited in those references (see for example “A TUNABLE SAW DUPLEXER” by David Pennunuri, Richard Kommrusch and Neal Mellen, 2000 IEEE Ultrasonics Symposium, pp 361-366; and “TUNABLE DUPLEXER HAVING MULTILAYER STRUCTURE USING LTCC” by Kouki Saitou and Keisuke Kageyama, 2003 IEEE MTT-S Digest, pp 1763-1766).
What is needed in the art is an improved architecture for a multiradio device to overcome some of the design challenges incorporating ever more radios in a multiradio device and interfacing them to antennas while meeting the technical performance requirements, without expanding the housing size of a handheld wireless multiradio device.